This invention relates generally to the initiation of crystallization of a supercooled salt solution, and more particularly, to the provision of a highly advantageous trigger that is easily deformable and is constructed to initiate such crystallization when the trigger is deformed, and which minimizes or prevents unwanted or inadvertent crystallization initiation.
Devices of the general type with which the present invention is concerned are described in U.S. Pat. No. 4,077,390 issued Mar. 7, 1978, to Stanley et al. for "Reusable Heat Pack Containing Supercooled Solution and Means for Activating Same"; however, such devices have tended to suffer from unreliable triggering of crystallization. For example, jarring of the actuator strips will at times inadvertently initiate crystallization. This greatly aggravates the user and reduces the practicality and utility of such devices.
Other patents which show and describe such triggers for use in such solutions are U.S. Pat. No. 4,379,448, issued Apr. 12, 1983, to Kapralis et al. for "Trigger to Initiate Crystallization"; U.S. Pat. No. 4,460,546, issued July 17, 1984, to Kapralis et al. for "Trigger to Controllably Initiate Crystallization"; and U.S. Pat. No. 4,532,110, issued July 30, 1985, to Kapralis et al. for "Protected Trigger to Controllably Initiate Crystallization". Patents related to other aspects of the device are U.S. Pat. No. 4,559,047, issued Dec. 17, 1985, to Kapralis et al. entitled "Heat Producing Mask and Use Thereof", and U.S. Pat. No. 4,580,547, issued Apr. 8, 1986, to Kapralis et al. entitled "Flexible Heat Pack Containing Super Cooled Salt Solution".
The patents hereinabove referenced relate to flexible packs containing supercooled salt solutions with trigger mechanisms having spaced slots or slits. The latter tend to pass supercooled fluid therethrough when the flexible pack is moved about, as during shipment; and it is found that unwanted crystallization of the salt solution can at times inadvertently occur, prior to ultimate manual flexing of the trigger by the user. There is need for a trigger construction that prevents or minimizes such inadvertent crystallization.